From ee488e2133e581967d13d5287d7bd654e9b2e2a6 Mon Sep 17 00:00:00 2001
From: Andrew Cooper <andrew.cooper3@citrix.com>
Date: Thu, 2 Jun 2016 14:19:00 +0100
Subject: [PATCH] xen/arm: Don't free p2m->root in p2m_teardown() before it has
been allocated
If p2m_init() didn't complete successfully, (e.g. due to VMID
exhaustion), p2m_teardown() is called and unconditionally tries to free
p2m->root before it has been allocated. free_domheap_pages() doesn't
tolerate NULL pointers.
This is XSA-181
Reported-by: Aaron Cornelius <Aaron.Cornelius@dornerworks.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Julien Grall <julien.grall@arm.com>
---
xen/arch/arm/p2m.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 838d004..6a19c57 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -1408,7 +1408,8 @@ void p2m_teardown(struct domain *d)
while ( (pg = page_list_remove_head(&p2m->pages)) )
free_domheap_page(pg);
- free_domheap_pages(p2m->root, P2M_ROOT_ORDER);
+ if ( p2m->root )
+ free_domheap_pages(p2m->root, P2M_ROOT_ORDER);
p2m->root = NULL;
--
2.1.4